node { background: yellow; }


 [ Bonn ] ..> [ Berlin ] -> [ Kassel ]
 [ Bonn ] .-> [ Koblenz ]
 [ Bonn ] -> [ Ulm ] -> [ Koblenz ]
 [ Ulm ] -> [ Bautzen ] -> [ Berlin ]

 [ 1Bonn ] ..> [ 1Berlin ] -> [ 1Kassel ]
 [ 1Bonn ] .-> [ 1Koblenz ]
 [ 1Bonn ] -> [ 1Ulm ] -> [ 1Koblenz ]
 [ 1Ulm ] -> [ 1Bautzen ] -> [ 1Berlin ]


 [ 2Bonn ] ..> [ 2Berlin ] -> [ 2Kassel ]
 [ 2Bonn ] .-> [ 2Koblenz ]
 [ 2Bonn ] -> [ 2Ulm ] -> [ 2Koblenz ]
 [ 2Ulm ] -> [ 2Bautzen ] -> [ 2Berlin ]